DESCRIPTION: The proposed research and training for this five-year Career Development Award (CDA-2) of Dr. Matthew Major, PhD, will contribute to the realization of the VA mission and vision by conducting studies that aim to reduce falls and improve the quality of life of older veterans with transtibial amputation (TTA)] while enhancing Dr. Major's skills to direct a dynamic research program of rehabilitation science as an independent investigator in the VA system. Previous studies have demonstrated that older persons with lower limb amputation are at a substantially increased risk of falling as compared to able-bodied age-matched controls and have reduced confidence in their balance, both contributing to their restricted mobility and daily activity. As upright balance is vital to safe mobility, an important consequence of elevated fall incidence is an increased risk of fall-related injuries that may lead to lost independence and early mortality. Due to the dearth of comprehensive controlled studies on this topic, the relationships between variables of postural control and fall risk in this population remain poorly understand and this has significantly hampered progress towards addressing this important concern for veterans with [TTA]. Therefore, the proposed research activities will involve a series of controlled experiments to develop much-needed insight into the sensory-motor mechanisms of upright balance and fall risk in older veterans with [TTA]. The two specific aims are: 1) identify discriminating biomechanical and clinical factors related to upright balance between older adults with [TTA] classified as [frequent fallers and controls], and 2) evaluate the motor control strategies employed by older adults with [TTA] when subjected to an unexpected perturbation during standing and walking. These research activities will be performed in the Jesse Brown VA Medical Center Motion Analysis Research Laboratory under the guidance of Dr. Steven Gard, an experienced VA Research Health Scientist of rehabilitation and prosthetics research. Information from this study will lead to the identification of sensory-motor variables related to fll risk that may be modified through targeted interventions and development of a clinically-relevant predictive model of falls. Dr. Major's career objective is to become a highly skilled independent investigator within the VA Rehabilitation Research and Development Service. Resulting from previous research and training, he has developed a solid foundation of skills related to investigating the biomechanics of human movement with specific focus on gait of lower limb prosthesis users. Dr. Major is proposing diverse training activities that will compliment his education in biomechanics by refining skills in amputee clinical care and motor control theory. His goal is to develop a productive VA research career aimed at improving functional balance and mobility of veterans with neuromuscular and musculoskeletal insult. His training plan includes formal education in prosthetics clinical education, clinical and translational sciences, project management, team leadership, and grant writing skills to develop his abilities as an independent VA scientist and effective leader. Dr. Major has assembled a well-qualified team of mentors who will provide expert guidance on various aspects of the proposed project in the form of directed readings and, most critically, exposure to the VA healthcare system such that he may develop a research program that is sensitive to the VHA patient care mission. The results of this research will facilitate pursuit of future research initiatives to explore design of theraputic interventions for improving postural control that may be integrated into the VA system of care, development of clinical diagnostic tools to accurately assess fall risk in older veterans with [TTA], inform VA prescription guidelines of current prostheses, and design future prosthetic devices that enhance functional balance. Importantly, these results will provide the basis for the submission of two VA Merit Awards that will be instrumental in transitioning Dr. Major to the role of an independent investigator working to fulfill the VHA patient care mission and vision.